/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.iotdb.db.protocol.mqtt;

import com.google.common.base.Preconditions;
import org.apache.commons.io.FileUtils;
import org.apache.iotdb.commons.file.SystemFileFactory;
import org.apache.iotdb.db.conf.IoTDBDescriptor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.ServiceLoader;

/**
 * PayloadFormatManager loads payload formatter from SPI services.
 */
public class PayloadFormatManager {
    private static final Logger logger = LoggerFactory.getLogger(PayloadFormatManager.class);

    // The dir saving MQTT payload plugin .jar files
    private static String mqttDir;
    // Map: formatterName => PayloadFormatter
    private static Map<String, PayloadFormatter> mqttPayloadPluginMap = new HashMap<>();

    static {
        init();
    }

    private static void init() {
        mqttDir = IoTDBDescriptor.getInstance().getConfig().getMqttDir();
        logger.info("mqttDir: {}", mqttDir);

        try {
            makeMqttPluginDir();
            buildMqttPluginMap();
        } catch (IOException e) {
            logger.error("MQTT PayloadFormatManager init() error.", e);
        }
    }

    public static PayloadFormatter getPayloadFormat(String name) {
        PayloadFormatter formatter = mqttPayloadPluginMap.get(name);
        Preconditions.checkArgument(formatter != null, "Unknown payload format named: " + name);
        return formatter;
    }

    private static void makeMqttPluginDir() throws IOException {
        File file = SystemFileFactory.INSTANCE.getFile(mqttDir);
        if (file.exists() && file.isDirectory()) {
            return;
        }
        FileUtils.forceMkdir(file);
    }

    private static void buildMqttPluginMap() throws IOException {
        ServiceLoader<PayloadFormatter> payloadFormatters = ServiceLoader.load(PayloadFormatter.class);
        for (PayloadFormatter formatter : payloadFormatters) {
            if (formatter == null) {
                logger.error("PayloadFormatManager(), formatter is null.");
                continue;
            }

            String pluginName = formatter.getName();
            mqttPayloadPluginMap.put(pluginName, formatter);
            logger.info("PayloadFormatManager(), find MQTT Payload Plugin {}.", pluginName);
        }

        URL[] jarURLs = getPluginJarURLs(mqttDir);
        logger.debug("MQTT Plugin jarURLs: {}", jarURLs);

        for (URL jarUrl : jarURLs) {
            ClassLoader classLoader = new URLClassLoader(new URL[]{jarUrl});

            // Use SPI to get all plugins' class
            ServiceLoader<PayloadFormatter> payloadFormatters2 =
                    ServiceLoader.load(PayloadFormatter.class, classLoader);

            for (PayloadFormatter formatter : payloadFormatters2) {
                if (formatter == null) {
                    logger.error("PayloadFormatManager(), formatter is null.");
                    continue;
                }

                String pluginName = formatter.getName();
                if (mqttPayloadPluginMap.containsKey(pluginName)) {
                    continue;
                }
                mqttPayloadPluginMap.put(pluginName, formatter);
                logger.info("PayloadFormatManager(), find MQTT Payload Plugin {}.", pluginName);
            }
        }
    }

    /**
     * get all jar files in the given folder
     *
     * @param folderPath
     * @return all jar files' URL
     * @throws IOException
     */
    private static URL[] getPluginJarURLs(String folderPath) throws IOException {
        HashSet<File> fileSet =
                new HashSet<>(
                        org.apache.commons.io.FileUtils.listFiles(
                                SystemFileFactory.INSTANCE.getFile(folderPath), new String[]{"jar"}, true));
        return org.apache.commons.io.FileUtils.toURLs(fileSet.toArray(new File[0]));
    }
}
